1. Field
Example embodiments relate to a mask assembly and a deposition apparatus for a flat panel display using the same. More particularly, example embodiments relate to a mask assembly and a deposition apparatus for a flat panel display using the same that are capable of preventing deformation of a pattern of the mask assembly due to the weight of a substrate during a deposition process and improving deposition precision.
2. Description of the Related Art
Flat panel display devices have been used as alternative display devices for cathode ray tube display devices due to their lightweight and slim characteristics. Examples of flat panel display devices may include liquid crystal display devices (LCDs), organic light emitting diode (OLED) display devices, and so forth. Among the flat panel display devices, e.g., the OLED display devices may have better brightness and larger viewing angle than the LCDs and may have a super-slim structure due to removal of a backlight unit.
The OLED display device may operate using a phenomenon in which an electron injected from a cathode into an organic thin film may be re-coupled with a hole injected from an anode to form an exciton. A specific waveform of light may be generated from the exciton energy to realize images. The OLED display device may include OLEDs having R, G and B organic emission layers in order to display full-color.
In order to selectively form a cathode, an anode, an organic thin film, etc., on a substrate of a conventional OLED display device, e.g., formed of glass, stainless steel or synthetic resin, a photolithography method or a deposition method may be used. For example, in the photolithography method, a photoresist may be applied to a certain region of the substrate, followed by wet-etching or dry-etching thereof to form predetermined patterns on the substrate. However, in the photolithography method, moisture may be introduced into the photoresist during a photoresist separation process or an etching process. Therefore, the organic thin film of the OLED display device may deteriorate due to the moisture in the photoresist.
In another example, in the deposition method, a mask assembly having a pattern including a plurality of slits may be aligned on the substrate, followed by material deposition, e.g., organic light emission layers emitting R, G and B colors deposited in a predetermined pattern, onto the substrate through the slits. However, in a conventional deposition apparatus for a flat panel display device using a conventional mask assembly, a center portion of the substrate may be bent toward the mask assembly due to weight of the substrate during the deposition process. As such, the pattern mask of the mask assembly may be pressed by the substrate and may be deformed, thereby causing inaccurate alignment and deposition of material on the substrate.